Hectograph roll



Maud? 1, W36, L. M. DIXON HECTOGRAPH ROLL Filed March 12, 1935 Lewis M DzXah INVENTOR BY (3:0 4 2n; @Aafw ATTO NEY Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE 8 Claims.

My invention relates to hectograph rolls and more particularly to a means for indicating their moisture content.

The object of my invention is to render it easy for the user of hectograph rolls to know when the coating material of the roll contains the optimum amount of moisture to produce the best service and most satisfactory results in use, and means indicating the procedure to follow in case the moisture content of the roll deviates therefrom.

As is well known by those skilled in the art, a complete hectograph roll, as usually marketed, consists of a spindle or core of wood or metal or other suitable material of standard uniform diameter, upon which is wound a blanket which consists of a strip of backing of some strong durable membraneous material, such as cloth, which usually has been treated to render it substantially waterproof. Upon the mid-portion of the backing is a coating of considerable thickness of a soft, pliable ink absorbent material, leaving the end portions of the backing uncoated for a short distance, and on the ends of the back- 0 ing there is often a metal binding strip called a clip.

The coating is usually a colloidal material in which gelatin forms a considerable or predominating part of the solid portion. The composition of the coating on the backing consists of from 10 to per cent. of gelatin dissolved in eighty-five to ninety per cent. of glycerine containing a small porportion of water.

In use, a master copy is prepared using hectoa graph ink, pencil, typewriter ribbon or carbon paper in the well known manner. All of these contain a large proportion of methyl or crystal violet dye. The master copy is placed in contact with the surface of the coating and a portion of the dye is absorbed by the gelatin composition.

After a short period of contact the master copy is removed from the surface of the gelatin and sheets of paper are laid one after another on the gelatin surface and receive an impression of the dye which has been absorbed into the coating from the master copy. Each copy so made removes from the surface a slight amount of the dye and also a slight amount of the glycerine and water from the coating.

When the gelatin and glycerine coating contains the right amount of water the proper amount of dye is absorbed from the master copy and a very slight amount of dye, glycerine and water is removed by the copies as they are made. If the gelatin-glycerine composition of the coating becomes too dry the surface becomes sticky and poor copies result, and a greater amount of glycerine and water and also some of the gelatin, is removed and the life of the roll is shortened.

To maintain or increase the water content the coating of the roll is wetted with a sponge and the roll rolled up to permit the added water to be absorbed into the coating. When this is done at regular and proper intervals the roll will remain full size for a longer time, give more and brighter copies and the copies will have less tendency to stick. This proper degree of moisture content in the gelatine-glycerine composition I refer to in this description and in the claims as the optimum moisture conten In order to maintain the coating of the roll at the proper degree of wetness or moisture content it has in the past been necessary to educate the user to be able to judge when the moisture condition is at its optimum by elaborate and detailed instructions and by practice with the use of hectograph rolls. This has been found quite unsatisfactory for the reason that many or most users do not acquire the requisite knowledge and skill or do not devote the necessary attention to the condition of the roll to secure the best results.

It is common practice to include with each roll full instructions for the maintenance of the roll in approximately the proper condition in respect to the moisture content. These instructions commonly call for one treatment in the summer and a different treatment in winter. For example in the winter, when artificial heat in oflices results in an atmosphere of low relative humidity, a hectograph roll exposed to such conditions dries out rather rapidly and requires the replacement of the evaporated water at frequent intervals. 0n the other hand, in the warmer weather the humidity may be high and less moisture is evaporated from the gelatin roll, in fact in very humid weather the gelatin coating may absorb moisture from the atmosphere and require that little if any additional water be applied to the roll.

The decision as to when to add water and how much and how often has heretofore been a matter of judgment on the part of the user and at times the user may be one of limited experience or quite inexperienced or lacking in good judgment as to the optimum degree of moisture in the roll in the absence of any method of determining this condition except by looking at the coating and feeling it.

It is one of the physical characteristics of the colloidal material used in making hectograph rolls that it increases in volume or swells upon the addition of water and decreases in volume or shrinks when the water content is reduced by evaporation, absorption by the copies, or otherwise. I have found that this change in volume can advantageously be utilized to serve as an indicator of the amount of moisture in the hectograph roll and also to indicate Whether moisture is present in excess or is deficient. Having once established the optimum moisture condition in a roll and ascertained the dimensions of the roll when in this condition, any subsequent change in the moisture condition of the gelatin composition will be reflected in the volume and therefore the dimensions of the roll.

It is customary to manufacture these rolls in lengths having about 15 feet of coating with an uncoated length of backing extending about 18 or 20 inches beyond the coating at each end and often with a metal clip or binding strip at each end of the backing. When such a blanket is rolled upon a spindle the outside diameter of the roll will ordinarily be in the neighborhood of 3 inches and a circumference in the neighborhood of II inches when the gelatin has the optimum moisture content. If such a roll is permitted to lose a portion of its moisture by evaporation the volume and therefore the thickness of the coating will decrease, and the circumferential 'measurement might decrease to 10%; inches or even less, depending upon the amount of moisture lost from the coating. Conversely, if moisture is added to the coating a swelling action takes place and the circumferential measurement of the roll might become 11 or 11% inches or even more. This circumferential measurement therefore offers a reliable indicator of moisture content of the coating, and also provides ready means for determining the same.

Other methods of determining when a roll contains the proper amount of moisture have been tried, such as by weighing and noting gain or loss in weight, or by calipering the diameter, but both these methods have their disadvantages. The weight method involves the use of aweighing device which may or may not be readily available when wanted and the method of measuring diameter with a caliper involves making several measurements and averaging them since the roll is not always, or even usually a true cylinder. The method of measuring or indicating variations in the circumference of the roll have been found not only more convenient but more accurate.

In addition to its accuracy and convenience, my method is self indicating-that is, the attention of the user is called to the moisture condition of the roll each time it is rolled up without any added operation such as weighing or calipering being necessary. Not only is the condition of the roll obvious to the operator who uses it, but a supervisor of a department using many rolls may at a glance observe whether the operators are keeping their individual rolls in proper condition for use.

My invention resides in a roll in which the terminal portion of the backing is provided with means for utilizing it to measure, or to indicate, the outside circumferential measurement of the roll and variations thereof from the normal, and

with means for indicating that measurement which corresponds to the condition of optimum moisture content in the coating of the roll.

As a part of, or in conjunction with, the means for indicating the desired circumferential measurement I include means for instructing, or making obvious to, the user how to recognize the desired measurement and what steps to take when the measurement is found to be too great or too small.

In the accompanying drawing I show in Fig. 1, a roll exemplary of my invention and in Fig. 2, a detail of a terminal portion thereof.

In the drawing I represents the usual spindle or core upon which hectograph rolls are customarily wound. The backing 2 is coated, except at its extremities, with a layer 3 of colloidal material which possesses the physical quality common to colloidal substances of changing its volume with changes of moisture content. The outer uncoated terminal portion of the backing 2 which, when wrapped about the roll, forms the external layer is preferably and customarily provided at each end with a clip or binding strip 4 of sheet metal. On the outer surface of the backing membrane 2 at the edge of the clip 4 I place a mark 5, or equivalent position indicating device such as a notch in the edge of the backing or a perforation therein designating the position of the edge of the clip when the roll is in its optimum condition of moisture content. The position indicating device 5 I place on each individual roll separately, and at a time and under the conditions when I know that the moisture content of the roll is at or substantially at its optimmn. Since either end of the blanket may be rolled first on the spindle, I may place these measurment indicating devices on one or both of the uncoated end positions of the backing.

I have found that when the moisture content varies from the optimum, resulting in the edge of the clip 4 either overlapping or not reaching the mark 5 by reason of the swollen or shrunken condition of the coating, the user is often at a loss to know whether, in a specific case, to increase or decrease the moisture content by wetting or drying the roll. Many users are not aware of the characteristic physical attribute of colloids which causes them to swell with increase of moisture and shrink with decrease of moisture. I have therefore included in my invention a means for indicating to the user the procedure to follow in case the end of the roll either overlaps or does not reach the mark 5.

This means for indicating procedure may take the form of printed instructions appearing on each side of the mark or references to instructions obtainable elsewhere or words indicating the condition to be remedied. In the drawing I have shown the latter method by placing the words Too wetlet dry 6 on one side of the mark 5 and the words Too dryadd water 1 on the other side of the mark, thus indicating to the user the necessary procedure to restore the coating to a condition of optimum moisture content.

Having described my invention I now state what I believe to be new and novel and for which I pray that Letters Patent be granted.

I claim:

1. A hectograph roll, a terminal portion of which is provided with means for indicating the moisture content of the coating and means indicating the procedure to be followed when the moisture content deviates from the optimum.

2. A hectograph roll, a terminal portion of which is provided with means for indicating a deviation of the circumferential measurement thereof from that which corresponds to the optimum moisture content of the coating.

3. A hectograph roll, a terminal portion of which is provided with means for indicating the direction of deviation of the circumferential measurement from that which corresponds to the optimum moisture content of the coating thereof.

4. A hectograph roll, a terminal portion of which is provided with means for indicating a dimensional condition corresponding to the optimum moisture content of the coating and any variation therefrom.

5. A hectograph roll having a clip on the end of its backing, an indicating marker on the said backing at a distance from the end of the clip equal to the circumference of the roll when the coating is in the condition of optimum moisture content.

6. A hectograph roll comprising in combination a spindle, a hectograph blanket rolled thereon composed of a strip of backing, a coating thereon of gelatinous composition, said coating covering less than the full length of the backing, a clip on the end of the backing, a marking device on the uncoated end of the backing at a distance from the outer end of the backing equal to the circumference of the roll when the coating has the optimum moisture content.

7. A hectograph roll comprising in combination a spindle, a hectograph blanket rolled thereon, comprising a backing and a coating thereon extending over the surface of the backing except for the end portions thereof, and a marker on the outer end portion of the backing at a distance from the end equal to the circumference of the roll when the coating thereof is in the condition of optimum moisture content.

8. A hectograph roll comprising in combination a spindle, a hectograph blanket roll thereon comprising a backing and a coating thereon extending over the surface of the backing except for the end portions thereof, a marker on the outer end portion of the backing at a distance from the end equal to the circumference of the roll when the coating thereof is in the condition of optimum moisture content and means indicating the procedure to be followed in case of deviation of the circumference from that corresponding to the optimum moisture content of the coating.

LEWIS M. DIXON. 

